The present invention relates to a grill shutter structure of a vehicle, and particularly relates to a grill shutter structure of a vehicle which comprises a shutter unit including a shutter member operative to be open or closed and a traveling-air guide member provided to extend forward from an outer peripheral edge portion of the shutter unit.
Conventionally, it is known to provide a grill shutter unit capable of adjusting the amount of traveling air introduced into an engine room through a traveling-air introductory port at a front grill or the like formed at a front end of a vehicle in order to prevent any improper combustion which may be caused by excessive cooling of an engine, a radiator and the like. The traveling air introduced into the engine room flows down a tunnel portion of a floor panel and other portions during a vehicle traveling, which may cause improper air turbulence around the vehicle. Accordingly, it has been desired, in order to prevent any traveling-resistance increase and fuel-economy (gas-mileage) deterioration of the vehicle caused by the traveling-resistance increase, that the grill shutter unit capable of adjusting the amount of traveling air introduced into the engine room is installed to the vehicle.
The grill shutter unit substantially comprises a shutter unit including a shutter operative to be open or closed for a traveling-air introductory port, an electromotive actuator operative to open or close the shutter, and others. A movable grill shutter for a vehicle disclosed in EP 2407333 A1 is arranged as a unit at a front grill opening portion, and it comprises a left-side first fin (left-side shutter) equipped with a first support shaft, a right-side second fin (right-side shutter) equipped with a second support shaft, a first output shaft operative to open or close the first fin, a second output shaft operative to open or close the second fin, and an actuator arranged between the first and second fins. Further, first and second joints are provided respectively between the first and second output shafts and the first and second support shafts.
It is also known, in order to improve the layout of a grill shutter unit and the design flexibility inside an engine room, to provide a structure in which the grill shutter unit is attached to a shroud member supporting a radiator, condenser and others, and the grill shutter unit and a traveling-air introductory port at a front grill or the like which is formed at a bumper face. According to a duct structure of a front portion of a vehicle disclosed in Japanese Patent Laid-Open Publication No. 2004-299522, a front grill formed at a bumper face and a traveling-air introductory port formed at a lower side of the front grill are provided, a duct device (grill shutter unit) attached to a radiator core support (shroud member) is provided between the front grill and the traveling-air introductory port and the radiator core support, and the duct device comprises plural duct portions operative to supply the traveling air to the radiator from the front grill and the traveling-air introductory port and shutters operative to pass or shut off the traveling air flowing down in the duct portions.
In general, the shroud member, which is of substantially a rectangular frame shape, is required to have a light weight, ensuring the support rigidity of the radiator, condenser and others as well as the strength as a vehicle-body constituting member. Therefore, the shroud member is made from a hard synthetic resin material containing glass fibers or the like, and attached to a vehicle body via an attaching bracket provided at front end portions of a pair of right-and-left front side frames. At front ends of the pair of right-and-left front side frames are arranged a pair of crash cans which extend forward respectively. A bumper reinforcement extending in a vehicle width direction is provided at respective front ends of the crash cans, and its front side area is covered with a bumper face. Thus, when a head-on collision of the vehicle happens, the crash cans provided at the front ends of the front side frames crush so that a collision load can be absorbed thereby and the safety of a passenger can be ensured.
It happens sometimes when rain or water, melt snow or the like which are splashed from a road surface come in through the traveling-air introductory port and some of them attaches itself onto surfaces of the shutters. Herein, since the water on the shutter surfaces causes the shutters to be frozen in the cold time, there is a concern that an opening/closing operation of the shutters may deteriorate. Accordingly, it has been proposed that an electric-conductive resilient member is attached to a lower end portion of each shutter so that the shutters can be prevented from being frozen in the cold time (see Japanese Patent Laid-Open Publication No. 2004-276712).
The grill shutter unit of the above-described second patent document is superior in layout and design flexibility, compared to the grill shutter unit of the above-described first patent document. Further, in the duct structure of the vehicle front portion of the above-described second patent document, since the grill shutter unit is arranged in back of and apart from the traveling-air introductory port, any breakage of the grill shutter unit which may be caused by interference of the grill shutter unit with the bumper reinforcement can be avoided in a case of a small collision of the vehicle. In a heavy collision of the vehicle in which the bumper reinforcement retreats greatly, however, since the distance between the bumper reinforcement and the front ends of the front side frames decreases according to compressive deformation of the crash cans, there is a concern that the grill shutter unit may be broken by the collision load. In the duct structure of the vehicle front portion of the above-described second patent document, since the grill shutter unit including the shutter unit and the duct portion is configured as a unit, it becomes necessary to exchange an entire part of the grill shutter unit even when part of the front side portion of the duct portion gets broken. Consequently, costs of repair may increase, so that there is a problem in that the repairability may deteriorate.
Further, in the duct structure of the vehicle front portion of the above-described second patent document, since the shutters are arranged in back of the traveling-air introductory port and also the duct portion extending longitudinally to guide the traveling air from the traveling-air introductory port to the shutter unit is provided, some traveling air comes into the engine room through a gap formed between a tip of the duct portion and the traveling-air introductory port, so that there is a concern that the fuel economy (gas mileage) may deteriorate because of the improper combustion caused by the excessive cooling or the traveling-resistance increase. Herein, while it may be considered to design such that the tip of the duct portion contacts the traveling-air introductory port tightly, assembling of both the grill shutter unit and the bumper reinforcement is not so easy that there is a problem in that the assembling workability may deteriorate. Moreover, in this case in which the tip of the duct portion contacts the traveling-air introductory port, the grill shutter unit may get broken easily because it comes to interfere with the bumper reinforcement even in the light vehicle collision.